A plate-shaped high power-density piezoelectric transformer with dual outputs

In this study, a high power-density dual-output piezoelectric transformer is proposed and experimentally investigated. This transformer consists of a lead zirconate titanate (PZT) ceramic plate with a size of 30 mm×5 mm×1 mm. It has a high mechanical quality factor Qm and high electromechanical coupling coefficient keff. The PZT ceramic plate is poled along the width direction. The electrodes of input and output parts are on the top and bottom surfaces of the ceramic plate and separated by narrow gaps. Lead wires are pressed on the electrodes by a proper elastic force. At a temperature rise lower than 20 °C, the piezoelectric transformer has a maximum output power density of 52.7 W/cm3 with an efficiency of 88%. The maximum efficiency of this piezoelectric transformer is 95%. Voltage gains larger than one and smaller than one are obtained in one transformer. By using a parallel combination of the two outputs of the proposed transformer, a higher output power density of 57.3 W/cm3 can be achieved at the temperature rise lower than 20 °C.